Calendar of Physics Talks Vienna

Non-Perturbative Thermal QCD: Gluon Condensates and AdS/QCD

Speaker:

Eugenio Megias (Universidad Autonoma de Madrid)

Abstract:

The theory of strong interactions is asymptotically free at high
energies and temperatures, and this allows one to use perturbative methods
to study it thermodynamic properties in this regime. Nevertheless close to
the phase transition non-perturbative effects become very important, and
usual perturbative approaches are not applicable. Then new non-perturbative
methods must be developed.
In this talk I will explore some of the features of the Polyakov loop,
heavy quark free energy and the thermodynamics of the confined and
deconfined phases of QCD within the AdS/QCD formalism, using a consistent
treatment based on 5D Einstein-dilaton gravity with a dilaton potential
first developed by E. Kiritsis et al. As a second part of my talk I will
explore the possible existence of the dimension two gluon condensate and the
role played to describe consistently the thermodnamics of QCD.

We consider Lovelock theories of gravity in the context of AdS/CFT. We show
that, for these theories, causality violation on a black hole background can
occur well in the interior of the geometry, thus posing more stringent
constraints than were previously found in the literature. Also, we find that
instabilities of the geometry can appear for certain parameter values at any
point in the geometry, as well in the bulk as close to the horizon. These
new sources of causality violation and instability should be related to CFT
features that do not depend on the UV behavior. We argue that it is possible
to obtain increasingly lower values for the shear viscosity to entropy
density ratio by the inclusion of more Lovelock terms.